Atomic irradiator



Dec: 21, 1965 2 Sheets-Sheet 1 Filed June 5, 1961 4/. S mm W mm Ma W6 I r ,m W M O/ I y a 5 4 2 W a /u g H x 4 3 Dec. 21, 1965 D. w. GOMBERT ATOMIC IRRADIATOR 2 Sheets-Sheet 2 Filed June 5, 1961 FIG, 5

FIG. 4

INVENTOR. Diezer' W. GomberZ W M It M Qfzys United States Patent O 3,225,203 ATOMIC IRRADIATOR Dieter W. Gombert, Itasca, IIL, assignor to Cook Electric Company, Chicago, Ill., a corporation of Delaware Filed June 5, 1961, Ser. No. 114,922 4 Claims. (Cl. 250-106) This invention relates to a new and improved device for subjecting specimens to atomic radiation from a radioactive source.

One object of the present invention is to provide an atomic irradiator having an irradiation chamber surrounded by a housing or shell for substantially preventing the escape of atomic radiation from the chamber, together with a device for easily and conveniently introducing specimens into said chamber.

A further object is to provide an irradiator of the foregoing character in which such device takes the form of a Wheel which is rotatable in the housing and which has a specimen holder movable between the outside of the housing and the irradiation chamber when the wheel is rotated.

Another object is to provide an atomic irradiator in which the radioactive source is movable in a pool of mercury or other liquid so as to vary the attenuation afforded by the liquid.

A further object is to provide such an irradiator in which the mercury or other attenuating liquid is contained in a receptacle which is sealed by a flexible bellows connected between the receptacle and the operating rod for the radioactive body.

Another object is to provide an irradiator of the foregoing character in which an adjusting screw is connected to the operating rod by a swivel coupling so that the position of the radioactive body in the attenuating liquid may readily be varied.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a front elevational view of an atomic irradiator to be described as an illustrative embodiment of the present invention.

FIG. 2 is a plan view of the irradiator.

FIG. 3 is an elevational sectional view, taken generally along a line 33 in FIG. 2.

FIG. 4 is a fragmentary horizontal section taken generally along a line 44 in FIG. 3.

The illustrated irradiator It) comprises a housing 12 containing an irradiation chamber 14 in which samples or specimens may be subjected to atomic radiation. The housing 14 affords adequate shielding for substantially preventing the escape of atomic radiation from the irradiation chamber. Thus, the illustrated housing 12 comprises a shield 16 in the form of upper and lower complementary interfitting masses 18 and 20 of lead or other efiicient shielding material. The shield 16 is made in two parts so that the shield may easily be assembled and disassembled. A stepped portion is provided on the shielding body 18 along the joint between the bodies 18 and 20 so as to prevent any beams of radiation from escaping at the joint.

The illustrated shield 16 is encased within a jacket 24 which may be made of steel or other structural material sufiiciently strong to support the great weight of the lead shield. In this case, the jacket 24 is in the form of upper and lower shells 26 and 28 which are joined along a horizontal plane by flanges 3t) and 32. A plurality of bolts 34 may be employed to secure the flanges together. The bolts may be welded in place to prevent them from being removed by mistake. Of course, the bo ts may be burned off with a cutting torch if disassembly of the irradiator becomes necessary.

In this case, the housing 12 is mounted on a cylindrical support 38 projecting upwardly from a frame or base 40. Casters 42 and 44 may be mounted on the base 41) so that the irradiator may readily be moved about. As shown, the casters 42 are solidly secured to the base, while the casters 44 are arranged to swivel.

In order that specimens or sample-s may readily and safely be moved into and out of the irradiation chamber 14, the irradiator 10 is provided with a specimen transfer member or wheel 46 which is rotatably mounted in the housing 12. In this case the wheel 46 is horizontal and is secured to a vertical operating shaft 48. However, the Wheel 46 could be mounted in any desired position. The transfer wheel 46 is made of lead or some other efiicient shielding material. The wheel 46 is mounted in an open ing 51 in the housing 12 and is adapted to close the opening so as to prevent the escape of atomic radiation therefrom.

In the illustrated construction, the weight of the transfer wheel 46 is supported by a main thrust bearing 52 at the lower end of the shaft 48. Additional bearings 54 and 56 are provided above and below the wheel 46 to support the shaft 48 in a vertical position. As shown, the shaft 43 extends upwardly above the housing 12 and is fitted with a hand wheel 58 whereby the wheel 46 may be rotated as desired. Of course, a drive motor may be connected to the shaft 48, if powered operation of the shaft is desired.

It will be seen that the front edge portion of the wheel 46 projects out of the housing 12, while the rear edge portion of the wheel extends into the irradiation chamber 14. One or more specimen holders 60 are provided on the wheel so that a specimen may be carried from the outside of the housing into the irradiation chamber 14 by rotating the wheel. The housing 12 has a pair of forwardly projecting lateral wings 61 and 62 which shield the lateral edge portions of the wheel 46, leaving only a narrow sector 63 at the front of the housing, in which the front edge portion of the wheel is exposed. The wheel 46 has a central portion 64 which is stepped to a greater thickness than the edge portion 65 of the Wheel, so as to prevent the escape of beams of radiation from the irradiation chamber 14.

In this case the specimen holders 60 take the form of openings or recesses in the edge portion of the wheel 46. It is convenient to provide two diametrically opposite specimen holders in the wheel as shown, although a single specimen holder would sufiice. As shown to advantage in FIG. 3, a lower wall 66 extends across the lower end of each specimen opening 64. This lower wall may be employed to support the specimens. The wall 66 may be made of aluminum or some other material which is virtually transparent to atomic radiation. The upper end of each opening 60 may be closed by an upper wall or cover 67 which may be removable or may be arranged to swing upwardly, as indicated in FIG. 1, so as to facilitate the insertion of specimens into the opening 60. iljlhe cover 67 may also be made of aluminum or the Provision is made for locking the transfer wheel 46 in either of its two positions in which one of the specimen holders is in the irradiation chamber 14. Thus, a locking pin or bar 68 may be inserted through aligned holes 6% and 70 in the housing 12 and the wheel 46. Two diametrically opposite holes 70 may be provided in the wheel 46. In the illustrated construction, the irradiation chamber 14 is provided with two sources of atomic radiation, in the form of radioactive bodies or plates 72, one disposed above and the other below the edge portion of the transfer wheel 46. The plates may be made of or may contain any desired radioactive material, such as cobalt-60 or cesium-137, for example. Each atomic source is provided with an attenuating arrangement '74 whereby the effective strength of the radiation from the source may be varied. Thus, the upper and lower plates 72 are movably mounted within upper and lower receptacles 76 filled with an attenuating liquid 78, preferably mercury. Each plate 72 is movable in the mercury, toward and away from the specimen holder 60 on the wheel 46. In this way, it is possible to vary the amount of mercury between the radioactive body and the specimen. Thus, the amount of radiation absorbed by the mercury may be varied.

As shown, operating rods 80 extend out of the receptacles 76 from the radioactive plates 72. To prevent any leakage of mercury, a metal bellows 82 is employed as a seal between the movable rod 80 and the corresponding receptacle 76. An expansion chamber 84 may be connected to each receptacle 76 to provide for the displacement of the mercury by the rod 80 and to allow for expansion and contraction of the mercury due to temperature variations. A passage 86 extends upwardly between each receptacle 76 and the corresponding expansion chamber 84. As the mercury expands or is displaced, it enters the expansion chamber, compressing any air or other gas that may be trapped therein. By means of swivel couplings $8, the rods 80 are connected to adjusting screws 90 which extend out of the housing 12. A hand wheel 92 may be connected directly to the upper end of the upper adjusting screw 90 so that it may be rotated manually. In this way, the position of the upper radioactive plate 72 may be varied. The projecting portion of the upper screw 90 may be calibrated with a suitable scale to indicate the position of the upper radioactive plate 72. Of course, provision could be made for operating the screws 90 by suitable motors.

For greater ease of operation, the lower screw 90, which is within the cylindrical supporting member 38, is coupled to an external screw 94 by means of a chain drive, comprising a chain 96 running between sprockets 98 and 100 on the screws 90 and 94. A hand wheel 102 may be mounted on the screw 94. In this case, the screw 94 is threaded through a supporting bracket 104. The screw 94- may be calibrated with a suitable scale to indicate the position of the lower radioactive plate 72. It is preferred that the sprockets 98 and 1% be of the same size, and that the screws 94) and 94 be made with the same pitch, so that the screw 94 will travel upwardly and downwardly in synchronism with the screw 99.

The irradiator is operated by inserting a specimen into the specimen holder 60 at the front of the wheei 46, and then rotating the wheel through 180 degrees to move the specimen into the irradiation chamber 14. This brings the other specimen holder 66 to the outside of the housing 12 so that any specimens therein may be removed. It will be evident that the insertion of the specimens is very easily accomplished because it involves only rotation of the wheel, without any need to lift any weight.

The strength of the radiation aiforded by the radioactive plates 72 may be varied by turning the hand wheels 92 and 1M so as to move the radioactive plates upwardly and downwardly in the mercury or other attenuating liquid 78. The mercury absorbs some of the radiation from the plates. The amount of radiation that is absorbed may be varied by moving each plate so as to increase or decrease the amount of mercury between the plate and the specimen.

Various other modifications, alternative constructlons and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

I claim:

1. In an irradiator for subjecting specimens to atomic radiation, the combination comprising a housing having an irradiation chamber therein, said housing including a shield for substantially preventing the escape of atomic radiation from said chamber, a wheel rotatably mounted in said housing and having an edge portion movable through said chamber, said housing having an opening therein for receiving a sectoral portion of said wheel, the remaining portion of said wheel projecting outside said housing to an accessible point, said wheel including shielding material for substantially preventing the escape of atomic radiation from said chamber through said opening, said wheel having a pair of diametrically opposite specimen holding notches in the edge portion thereof and movable from said accessible point into said irradiation chamber by rotation of said wheel, each of said notches having a lower wall therein for supporting specimens to be irradiated, a shaft connected to said wheel and extending out of said housing for rotating said Wheel, upper and lower radioactive plates in said irradiation chamber above and below the edge portion of said wheel, each of said notches being movable into register with said plates for irradiating the specimens in said notches, upper and lower receptacles received around said upper and lower plates and filled with mercury so as to immerse said plates, each of said plates having an operating rod connected to said plate and extending out of the corresponding receptacle, a flexible metal bellows connected between said receptacle and said rod and forming a seal therebetween, an adjusting screw extending out of said housing, and a swivel coupling connected between said adjusting screw and said rod, whereby said screw is operative to move said plate in said mercury toward and away from said wheel so as to afford variable attenuation of the atomic radiation penetrating through said mercury and into said notches in said wheel.

2. In an irradiator for subjecting specimens to atomic radiation, the combination comprising a housing having an irradiator chamber therein, said housing including a shield for substantially preventing the escape of atomic radiation from said chamber, a wheel rotatably mounted in said housing and having an edge portion movable through said chamber, said housing having a cylindrically curved cavity therein for receiving a sectoral portion of said wheel, the remaining portion of said wheel projecting outside said housing to an accessible point, said wheel including shielding material for substantially preventing the escape of atomic radiation from said chamber through said cavity, said wheel having a pair of diametrically opposite specimen holding notches in the edge portion thereof and movable from said accessible point into said irradiation chamber by rotation of said wheel, each of said notches having a lower wall therein for supporting specimens to be irradiated, a shaft connected to said wheel and extending out of said housing for rotating said wheel, upper and lower radioactive bodies in said irradiation chamber above and below the edge portion of said wheel, each of said notches being movable into register with said bodies for irradiating the specimens in said notches, upper and lower receptacles received around said upper and lower bodies and filled with a liquid so as to immerse said bodies, each of said bodies having an operating rod connected thereto and extending out of the corresponding receptacle, a flexible metal bellows connected between said receptacle and said rod and forming a seal therebetween, an adjusting screw extending out of said housing, and a swivel coupling connected be tween said adjusting screw and said rod whereby said screw is operative to move said body in said liquid toward and away from said wheel so as to afford variable attenuation of the atomic radiation penetrating into said notches in said wheel.

3. In an irradiator for subjecting specimens to atomic radiation, the combination comprising a housing having an irradiation chamber therein, said housing including a shield for substantially preventing the escape of atomic radiation from said chamber, a wheel rotatably mounted in said housing and having an edge portion movable through said chamber, said housing having a cylindrically curved cavity therein for receiving a sectoral portion of said wheel, the remaining portion of said wheel projecting outside said housing to an accessible point, said Wheel including shielding material for substantially preventing the escape of atomic radiation from said chamher through said cavity, said wheel having at least one specimen holding notch in the edge portion thereof and movable from said accessible point into said irradiation chamber by rotation of said wheel, said notch having a lower wall therein for supporting specimens to be irradiated, a shaft connected to said wheel and extending out of said shield for rotating said wheel, at least one radioactive body disposed outside said wheel and in said irradiating chamber opposite the edge portion of said wheel, said notch being movable into registration with said body for irradiating the specimen in said notch, a receptacle received around said radioactive body and filled with a liquid so as to immerse said body, said body having an operating rod connected thereto and extending out of said receptacle, a flexible bellows connected between said receptacle and said rod and forming a seal therebetween, an adjusting screw extending out of said shield, and a swivel coupling connected between said adjusting screw and said rod, whereby said screw is operative to move said body in said liquid toward and away from said wheel so as to afford variable attenuation of the atomic radiation from said body.

4. In an irradiator for subjecting specimens to atomic radiation, the combination comprising a housing having an irradiation chamber therein, said housing including a shield for substantially preventing the escape of atomic radiation from said chamber, a wheel rotatably mounted in said housing and having an edge portion movable through said chamber, said housing having a cylindrically curved cavity therein for receiving a sectoral por tion of said wheel, the remaining portion of said wheel projecting outside said housing to an accessible point, said wheel including shielding material for substantially preventing the escape of atomic radiation from said chamber through said cavity, said wheel having at least one specimen holding notch in the edge portion thereof and movable from said accessible point into said irradiation chamber by rotation of said wheel, said notch having a lower wall therein for supporting specimens to be irradiated, a shaft connected to said Wheel and extending out of said shield for rotating said wheel, at least one radioactive body disposed outside said wheel and in said irradiating chamber opposite the edge portion of said wheel, said notch being movable into registration with said body for irradiating the specimen in. said notch, a receptacle received around said radioactive body and filled with a liquid so as to immerse said body, said body having an operating rod connected thereto and extending out of said receptacle, a flexible bellows connected between said receptacle and said rod and forming a seal therebetween, and means connected to said rod and extending out of said shield for moving said body in said liquid toward and away from said wheel so as to afford variable attenuation of atomic radiation from said body.

References Cited by the Examiner UNITED STATES PATENTS 2,490,298 12/1949 Ghiorso et a1 250-106 2,687,477 8/1954 Pfalf 250-106 2,790,086 4/1957 Beyer et a1 250-106 2,843,753 7/1958 Meeder 250-106 2,866,905 12/1958 Yeomans 250-106 2,891,167 6/1959 Coleman et a1 250-108 2,933,607 4/1960 Friedman 250-435 2,935,616 5/1960 Smith et al. 250-108 2,936,378 5/1960 Jensen 250-106 RALPH G. NILSON, Primary Examiner.

ARTHUR GAUSS, Examiner. 

1. IN AN IRRADIATOR FOR SUBJECTING SPECIMENS TO ATOMIC RADIATION, THE COMBINATION COMPRISING A HOUSING HAVING AN IRRADIATION CHAMBER THEREIN, SAID HOUSING INCLUDING A SHIELD FOR SUBSTANTIALLY PREVENTING THE ESCAPE OF ATOMIC RADIATION FROM SAID CHAMBER, A WHEEL ROTATABLY MOUNTED IN SAID HOUSING AND HAVING AN EDGE PORTION MOVABLE THROUGH SAID CHAMBER, SAID HOUSING HAVING AN OPENING THEREIN FOR RECEIVING A SECTORAL PORTION OF SAID WHEEL, THE REMAINING PORTION OF SAID WHEEL PROJECTING OUTSIDE SAID HOUSING TO AN ACCESSIBLE POINT, SAID WHEEL INCLUDING SHIELDING MATERIAL FOR SUBSTANTIALLY PREVENTING THE ESCAPE OF ATOMIC RADIATION FROM SAID CHAMBER THROUGH SAID OPENING, SAID WHEEL HAVING A PAIR OF DIAMETRICALLY OPPOSITE SPECIMEN HOLDING NOTCHES IN THE EDGE PORTION THEREOF AND MOVABLE FROM SAID ACCESSIBLE POINT INTO SAID IRRADIATION CHAMBER BY ROTATION OF SAID WHEEL, EACH OF SAID NOTCHES HAVING A LOWER WALL THEREIN FOR SUPPORTING SPECIMENS TO BE IRRADIATED, A SHAFT CONNECTED TO SAID WHEEL AND EXTENDING OUT OF SAID HOUSING FOR ROTATING SAID WHEEL, UPPER AND LOWER RADIOACTIVE PLATES IN SID IRRADIATION CHAMBER ABOVE AND BELOW THE EDGE PORTION OF SAID WHEEL, EACH OF SAID NOTCHES BEING MOVABLE INTO REGISTER WITH SAID PLATES FOR IRRADIATING THE SPECIMENS IN SAID NOTCHES, UPPER AND LOWER RECEPTACLES RECEIVED AROUND SAID UPPER AND LOWER PLATES AND FILLED WITH MERCURY SO AS TO IMMERSE SAID PLATES, EACH OF SAID PLATES HAVING AN OPERATING ROD CONNECTED TO SAID PLATE AND EXTENDING OUT OF THE CORRESPONDING RECEPTACLE, A FLEXIBLE METAL BELLOWS CONNECTED BETWEEN SAID RECEPTACLE AND SAID ROD AND FORMING A SEAL THEREBETWEEN, AN ADJUSTING SCREW EXTENDING OUT OF SAID HOUSING, AND A SWIVEL COUPLING CONNECTED BETWEEN SAID ADJUSTING SCREW AND SAID ROD, WHEREBY SAID SCREW IS OPERATIVE TO MOVE SAID PLATE IN SAID MERCURY TOWARD AND AWAY FROM SAID WHEEL SO AS TO AFFORD VARIABLE ATTENUATION OF THE ATOMIC RADIATION PENETRATING THROUGH SAID MERCURY AND INTO SAID NOTCHES IN SAID WHEEL. 